This invention relates to a mold and a method for casting metal parts within a sand cavity, within which metal chill plates are located, to produce hardened surface areas at predetermined locations on the parts.
In industrial applications, it is common to cast metal parts within a sand mold and, thereafter, harden preselected locations on the parts by heat treating or other known procedures. By way of example, automotive type engine cam shafts are typically cast in sand molds. Later, their projections or lobes are heat treated or nitrided or otherwise processed to harden the peripheral surfaces of the lobes. Other industrial parts, that are made of ferrous metals or alloys, are similarly manufactured.
In many cases, it would be desirable to harden selected areas on the surface of a casting during the casting process in order to reduce the number of manufacturing steps required for hardening after casting. Thus, attempts have been made in the past to utilize chills, that is, metal inserts arranged within or around the casting cavities of a mold. These chills rapidly cool molten metal poured into the mold cavity and, therefore, increase the surface hardness of the rapidly chilled areas. However, chill devices are relatively awkward to handle and to position properly during the preparation of a mold for casting molten metal. In use, they generally require additional labor and time. Chills are particularly awkward to use where the cast part has a considerable number of locations which require chill induced surface hardness.
Particularly in the case of automotive engine cam shafts and similar types of engine parts, the utilization of strategically located chills could materially reduce the number of steps needed for post-casting hardening of selected locations. But this requires a system for rapidly and easily handling, positioning and fixing the chills within a sand casting mold. Thus, the invention herein is concerned with a mold and a method utilizing strategically located chill plates in a manner which is simple and inexpensive so as to permit the use of such chill plates in mass production casting operations.